Alloy



United States Patent Ofiice ALLOY Wadsworth, and Arthur B. Michael, assignors to Fansteel Metallurgical Ser. No. 638,210 74) Leonard F. Yntema, Lake Forest, lll., Corporation No Drawing. Filed Feb. 5, 1957,

7 Claims. (Cl. 75-1 The present invention relates to alloys of columbium and more particularly to columbium alloys which, compared to substantially pure columbium metal, have greatly improved strength characteristics and resistance to oxidation at elevated temperatures of the order of 1300 C. and higher.

Substantially pure columbium metal has many desirable properties which make it potentially useful as a structural metal at high temperatures. Thus, for example, it has a melting point of about 245 C. and it possesses the same strength properties at elevated temperatures (of the order of 1300 C. and higher) as pure molybdenum, the refractory metal generally used heretofore for high temperature applications. In contrast to molybdenum, Which cannot be Worked at room temperature, but must be hot-worked, the refractory metal columbium can be cold worked. easier to fabricate and can be to cracking.

Because of the above mentioned properties of columbium, it has been suggested to use this metal in the form of jet turbine blades and buckets, rocket nozzles, and the like, where such members are subjected to high temperature conditions and to great thermal and physical 3,314,785 Patented Apr. 18, 1967 ders of 99 percent purity.

The term atomic percent of an element as used herein means the percentage of the total number of atoms in a mass of the alloy which are atoms of that particular element. The term percent of an element as used herein means the percentage of the total weight of a mass of the alloy which is the weight of that particular element.

Following are examples of the preparation and test results of columbium alloys of this invention:

Example I presintered at a temperature of about 2000 C. for about tWo hours in a vacuum of about 1 or 2 microns. Other conventional presintering conditions may be used.

The are melting procedures may be carried out in argon, a mixture of argon and helium, or in other inert gas.

The resulting arc melted alloy when tested for oxidation resistance in air at 2000 F. for sixteen hours is markedly superior in resistance to oxidation compared to unalloyed arc melted columbium metal.

gree of deformation as a function of time Was noted, and this is referred to herein as resistance to deformation. Example II The resulting arc melted columbium alloy when tested for oxidation resistance in air by subjecting a test specimen to the atmosphere at 2000 F. for a period of sixteen hours underwent an oxidation penetration of 0.015 cm.

This result is to be compared with an oxidation penetration of 0.085 cm. for unalloyed arc melted columbium subjected to the same conditions for the same period of time.

The strength of this alloy is two (2) times as great as unalloyed arc melted columbium metal tested under the same conditions, based on resistance to deformation of test specimens at elevated temperatures of between 2000 F. and 2200 F.

Example III A columbium alloy composition consisting of approximately 90.6 percent (95 atomic percent) columbium and 9.4 percent atomic percent) tungsten was prepared by powder metallurgy technique wherein 2000 grams of columbium powder and 207 grams of tungsten powder were intimately mixed and blended and the resulting powder mix pressed and sintered into an alloy bar. The blend was pressed at a pressure of 50 t.s.i. to form a green compact which was then sintered at a temperature of about 2000 F. for about two hours in a vacuum of about 1 or 2 microns.

A test specimen of this alloy bar when tested for oxidation resistance in air at 2000 F. for sixteen hours underwent an oxidation penetration of 0.013 cm. This compares with an oxidation penetration of 0.085 cm. for unalloyed arc melted columbium, subjected to the same conditions for the same period of time.

Another test specimen from this alloy when tested for strength characteristics based on resistance to deformation at elevated temperatures of between 2000 F. to 2200 F. showed that this alloy has two and one-half (2 /2) times the strength of unalloyed arc melted columbium metal tested under the same conditions.

Example IV A columbium alloy consisting of 82 percent (90 atomic percent) columbium and 18 percent atomic percent) tungsten was prepared by are melting a presintered electrode made from the indicated amounts of the metals as described in Example I, in a mixture of helium and argon.

The resulting arc melted columbium alloy when tested for oxidation resistance in air by subjecting a test specimen to the atmosphere at 2000 F. for a period of sixteen hours underwent an oxidation penetration of 0.010 cm. and when subjected for a period of sixty-six hours, underwent an oxidation penetration of 0.090 cm. On the other hand, unalloyed arc melted columbium when subjected to the same conditions for sixteen hours undergoes an oxidation penetration of 0.085 cm. and for sixtysix hours undergoes an oxidation penetration of 0.345 cm.

Another test specimen from this alloy, when tested for strength characteristics based on resistance to deformation at elevated temperatures of 2000 F. to 2200 F., showed that this alloy has three (3) times the strength of unalloyed arc melted columbium metal tested under the same conditions. I

Example V A columbium all-oy consisting of 67 percent (80 atomic percent) columbium and 33 percent (20 atomic percent) tungsten was prepared by are melting a presintered electrode made from the indicated amounts of the metals as described in Example I, in a mixture of helium and argon.

The resulting arc melted columbium alloy when tested for oxidation resistance in air by subjecting a test specimen to the atmosphere at 2000 F. for a period of sixteen hours underwent an oxidation penetration of 0.005 cm. This result is to be compared with an oxidation penetration of 0.085 cm. for unalloyed arc melted columbium subjected to the same test conditions for the same period of time.

The strength of this alloy is at least three and one-half (3 /2) times as great as unalloyed arc melted columbium metal tested under the same conditions. The strength tests were based on resistance to deformation of test specimens at elevated temperatures of 2000 F. to 2200 F.

Example VI A columbium alloy consisting of 54.2 percent (70 atomic percent) columbium and 45.8 percent (30 atomic percent) tungsten was prepared by are melting a presintered electrode of the indicated amounts of the metals made as described in Example I, in a mixture of helium and argon.

The resulting arc melted columbium alloy when tested for oxidation resistance in air by subjecting a test specimen to the atmosphere at 2000 F. for a period of sixteen hours underwent an oxidation penetration of 0.002 cm. and when subjected to the same conditions for sixtysix hours underwent an oxidation penetration of 0.039 cm. Unalloyed arc melted columbium when tested under the same conditions for sixteen hours undergoes an oxidation penetration of 0.085 cm. and for sixty-six hours undergoes an oxidation penetration of 0.354 cm.

The strength of this alloy is at least three and threequarter (3%) times as great as unalloyed arc melted columbium metal tested under the same conditions. These tests were based on resistance to deformation of test specimens at elevated temperatures of 2000 F. to 2200 F.

Example VII A columbium alloy consisting of 33 percent (50 atomic percent) columbium and 67 percent (50 atomic percent) tungsten was prepared by arc melting a presintered electrode of the indicated amounts of the metals made as described in Example I, in a mixture of helium and argon.

The resulting arc melted columbium alloy When tested for oxidation resistance in air by subjecting a test specimen to the atmosphere at 2000 F. for a period of sixteen hours underwent an oxidation penetration of 0.001 cm. This result is to :be compared with an oxidation penetration of 0.085 cm. for unalloyed arc melted columbium subjected to the same test conditions for the same period of time.

The strength of this alloy is at least four (4) times as great as unalloyed arc melted columbium metal tested under the same conditions. These tests were based on resistance to deformation of test specimens at elevated temperatures of 2000 F. to 2200 F.

Example VIII A columbium alloy composition of 99.49 percent (995 atomic percent) columbium and 0.51 percent (0.5 atomic percent) molybdenum was prepared by are melting a presintered electrode of the indicated amounts of the metals made as described in Example I, in a mixture of helium and argon.

The resulting arc melted alloy when tested for oxidation resistance in air at 2000 F. for sixteen hours was markedly superior in resistance to oxidation to unalloyed arc melted columbium metal.

This alloy is about one and one-half (1 /2) times greater in strength than unalloyed arc melted columbium as determined by resistance to deformation at an elevated temperature of 2000 F. to 2200 F.

Example IX A columbium alloy consisting of 96.9 percent (97 atomic percent) columbium and 3.1 percent (3 atomic percent) molybdenum was prepared by are melting a presintered electrode of the indicated amounts of the metals made as described in Example I, in a mixture of helium and argon.

The resulting arc melted columbium alloy when tested for oxidation resistance in air by subjecting a test specimen to the atmosphere at 2000 F. for a period of sixteen The strength of this alloy is at least two (2) times as great as unalloyed arc melted columbium metal tested under the same conditions. These tests were based on resistance to deformation at elevated temperatures of 2000 F. to 2200 F.

Example X made as described in and argon.

The resulting arc melted columbium alloy when tested for oxidation resistance in air by subjecting a test specimen to the atmosphere at 2000 F. for a period of sixteen hours underwent an oxidation penetration of 0.012 compared with an oxidation penetration of 0.085 cm. for unalloyed arc melted columbium.

The strength of this alloy is at least two and one-half (2 /2) times as great as unalloyed arc melted columbium metal tested under the same conditions. These tests were based on resistance to deformation of test specimens at elevated temperatures of 2000 F. to 2200 F.

Example XI A columbium alloy consisting of 79.5 percent (80 atomic percent) columbium mens at elevated temperatures of 2000 F. to 2200 F.

balance being substantially all columbium.

Alloys comprising from about 0.52 percent (0.51 atomic percent) to about 66.9 percent (49.9 atomic percent) of a.mixture of tungsten and molybdenum, the balance being substantially all columbium have the desired properties of oxidation resistance and high strength at elevated temperatures as the alloys of the foregoing It is important to note that the molybdenum content of the columbium-tungsten-molybdenum alloy should be no greater than atomic percent of the alloy.

It has been found that the oxidation resistance of the alloys of this invention (columbium-tungsten, columbium- .molybdenum, or columbium-tungsten-molybdenum) as well as the strength characteristics, may be further improved by incorporating in the alloys from about 0.1 percent to 2 percent silicon or 0.1 percent to 2.0 percent aluminum, as well as mixtures of these metals, wherein the total weight of the combined aluminum and silicon does not exceed 2.0 percent in the columbium base alloy.

Example XII A columbium base alloy consisting of 65.55 percent (77 atomic percent) columbium, 33.7 percent (20 atomic percent) tungsten, and .75 percent (3 atomic percent) aluminum in the form of aluminum columbide (Al Cb) Example XIII percent 77 atomic perwas prepared by arc from the indicated amounts of these metals as described in Example I, in a mixture of helium and argon.

The resulting arc melted columbium alloy when tested for oxidation resistance in air by subjecting a test specimen to the atmosphere at 2000 F. for a period of sixteen hours underwent an oxidation penetration of 0.0035 cm. This result is to be comparedwith an oxidation penetration of 0.085 cm. for unalloyed arc melted columbium.

The strength of this alloy is at least three and one half (3 /2) times as great as unalloyed arc melted columbium metal tested under the same conditions. These tests were based on resistance to deformation of test specimens at elevated temperatures of 2000 F. to 2200 F.

To the columbium-tungsten, columbium-molybdenum, columbium-tungsten-molybdenum alloys of this invention Example XIV A columbium alloy consisting percent) made by arc melting a presintered electrode made from the indicated amounts of these metals as described in Example I, in a mixture of helium and argon.

The resulting arc melted columbium alloy when tested for oxidation resistance in air by subjecting a. test specimen to the atmosphere at 2000 F. for a period of sixteen hours underwent an oxidation penetration of 0.057 cm. This result is to be compared with an oxidation penetration of 0.085 cm. for unalloyed arc melted columbium.

The strength of this alloy is at least two (2) times as great as unalloyed arc melted columbium metal tested under the same conditions. These tests were based on resistance to deformation of test specimens at elevated temperatures of 2000 F. to 2200 F.

Example XV A columbium alloy consisting of 68 percent (67 atomic percent) columbium, 20 percent atomic percent) tungsten, and 12 percent (23 atomic percent) titanium was prepared by are melting a presintered electrode made from the indicated amounts of these metals as described in Example I, in a mixture of helium and argon.

The resulting arc melted columbium alloy when tested for oxidation resistance in air by subjecting a test specimen to the atmosphere at 2000 F. for a period of sixteen hours underwent an oxidation penetration of 0.023 cm. This result is to be compared with an oxidation penetration of 0.085 cm. for unalloyed arc melted columbium.

The strength of this alloy is at least two and one-half (2 /2) times as great as unalloyed arc melted columbium metal tested under the same conditions. These tests were based on resistance to deformation of test specimens at elevated temperatures of 2000 F. to 2200 F.

Example XVI A columbium alloy consisting of 86.8 percent (86 atomic percent) columbium, 8 percent (4 atomic percent) tungsten and 5.2 percent (10 atomic percent) titanium was prepared by are melting a presintered electrode made from the indicated amounts of the metals as described in Example I, in a mixture of helium and argon.

The resulting arc melted columbium alloy when tested for oxidation resistance in air by subjecting a test specimen to the atmosphere at 2000 F. for a period of sixteen hours underwent an oxidation penetration of 0.011 cm. This result is to be compared with an oxidation penetration of 0.085 cm. for unalloyed arc melted columbium.

The strength of this alloy is at least two (2) times as great as unalloyed arc melted columbium metal tested under the same conditions. These tests were based on resistance to deformation of test specimens at elevated temperatures of 2000 F. to 2200 F.

The strength characteristics of the alloys comprised of columbium, tungsten and titanium, columbium, molybdenum and titanium, and columbium, tungsten, molybdenum and titanium, may be further improved by incorporating in the alloys from 0.1 percent to 2.0 percent silicon or 0.1 percent to 2.0 percent aluminum, as well as mixtures of these metals, wherein the total weight of the combined aluminum and silicon does not exceed 2.0 percent in the columbium base alloy.

Following is an example of a columbium base alloy of this invention incorporating tungsten, molybdenum, titanium, and silicon and aluminum.

Example XVII A columbium alloy consisting of 86.6 percent (80 atomic percent) columbium, 4.3 percent (2 atomic percent) tungsten, 2.2 percent (2 atomic percent) molybdenum, 5.6 percent (10 atomic percent) titanium, .7 percent (2 atomic percent) silicon and .6 percent (2 atomic percent) aluminum was prepared by are melting a presintered electrode made from the indicated amounts of the metals as described in Example I, in an atmosphere of a mixture of helium and argon gases.

The resulting arc melted columbium alloy when tested for oxidation resistance in air by subjecting a test specimen to the atmosphere at 2000 F. for a period of sixteen hours underwent an oxidation penetration of 0.009 cm. This result is to be compared with an oxidation penetration of 0.085 cm. for unalloyed arc melted columbium.

The strength of this alloy is at least two and one-half (2 /2) times as great as unalloyed arc melted columbium metal tested under the same conditions. These tests were based on resistance to deformation at elevated temperatures of 2000 F. to 2200 F.

The foregoing detailed description is given for clearness of understanding of the invention, and no unnecessary limitations should be understood therefrom, for some modification will be obvious to those skilled in the art.

We claim:

1. A columbium alloy which is composed essentially of: columbium and tungsten, there being from about 0.99 percent to about 67 percent tungsten and the balance being substantially all columbium.

2. A columbium alloy which is composed essentially of columbium and tungsten, there being from about 18 percent to about 45.8 percent of tungsten, the balance being substantially all columbium.

3. A columbium alloy which is composed essentially of. columbium; a metal selected from the group consisting of tungsten, molybdenum, and mixtures thereof, the content of tungsten when selected being from about 0.99 percent to about 67 percent, the content of molybdenum when selected being from about 0.51 percent to about 20.5 percent, and the content of mixtures of tungsten and molybdenum when selected being from about 0.52 percent to about 66.3 percent, the maximum molybdenum being about 20.5 percent; and from about 2 percent to about 20 percent titanium; the balance being substantially all columbium.

4. A high temperature ternary alloy composed of, by weight: about 50 to 70% niobium, about 15 to 30% tungsten, and about 2 to 15% titanium.

5. A high temperature alloy consisting essentially of by weight about 10 to 30% tungsten, 2 to 15% titanium, up to 15 molybdenum, and the balance being essentially columbium.

6. A high temperature alloy consisting essentially of by weight about 0.2% to 2% aluminum, about 4% to 15% molybdenum, and the balance being essentially columbium.

7. A columbium base alloy consisting essentially of by weight about 911% molybdenum, about 37% titanium, about 10% tungsten, about 0.5-2% aluminum and the balance substantially all columbium.

References Cited by the Examiner UNITED STATES PATENTS 1,811,487 6/1931 Belding 75--174 2,754,203 7/1956 Vordahl 75175.5 2,754,204 7/1956 Jaffee et al 75-1755 2,822,268 2/1958 Hix 75174 2,838,395 6/1958 Rhodin 75-174 2,838,396 6/1958 Rhodin 75-174 OTHER REFERENCES H. Buckle: Structure and Microhardness of Binary DAVID L. RECK, Primary Examiner.

CLAUDE A. LEROY, MARCUS U. LYONS, NATHAN MARMELSTEIN, RAY K. WINDHAM, HYLAND BIZOT, Examiners.

N. A. RAUTIOLA, W. B. NOLL, W. C. TOWNSEND,

C. N. LOVELL, Assistant Examiners. 

7. A COLUMBIUM BASE ALLOY CONSISTING ESSENTIALLY OF BY WEIGHT ABOUT 9-11% MOLYBDENUM, ABOUT 3-7% TITANIUM, ABOUT 10% TUNGSTEN, ABOUT 0.5-2% ALUMINUM AND THE BALANCE SUBSTANTIALLY ALL COLUMBIUM. 